Standardization for Dual Energy X-ray Absorptiometry

Cho, Jin A; Kim, Sang Woo; Kim, Auk; Ku, Ja Ran; Kim, Yong Tae; Yim, Chang Hoon; Han, Ki Oak; Chung, Ho Yeon; Han, In Kwon; Min, Hun Ki

Abstract

OBJECTIVES
Bone densitometry is a current method for evaluating skeletal status, assessing osteoporosis, and determining fracture risk. DEXA has rapidly become a dominent method for evaluating skeletal status. But the comparison of patient data among different DEXA scanners is complicated because the instruments show differences in scanner design, bone mineral calibration, and analysis algorithms. The purpose of this study is making standardization of DEXA and comparability among different DEXA system.
METHODS
Posteroanterior lumbar spine (L2-IA) measurements of healthy 83 racially homogenous Korean women, age 38-66 years (mean +/- 516, range of BMD 0.624-1.574g/cm) were obtained on a Lunar DPX-L, a Hologic QDR-2000, and a Norland XR-36. All sujects had no spinal deformities, ostophytes, fracture and scoliosis on thoracolumbar spinal X-ray. We performed the measurement of BMD in each subjects with different three scanners at the same time.
RESULTS
The results of cross-calibration spinal BMD (L2-4, g/cm2) in patient study (r2=0.972-0.974); Lunar DPX-L=(1.149 X Hologic)+0.008=(1.022 X Norland)+0.137, Hologic QDR-2000=(0.847 X Lunar)+0.019= (0.876 X Norland)+0.124, and Norland XR-36=(0.954 X Lunar)-0.107=1.110 X Hologic)-0.113. The average absolute difference in patients` spinal BMD values (L2-L4) between Lunar and Hologic was 0.146g/cm2 (14%); it was 0.156g/cm2 (15%) between Lunar and Norland and 0.010g/cm2 (1%) between Hologic and Norland.
CONCLUSIONS
The formula of this cross-calibration shows good correlation. We conclude that it is possible to compare the different spinal BMD values obtained on the different DEXA scanners.